Apparatus and method for removing selected sheets from the lower bridge of a corrugated paper board manufacturing machine

ABSTRACT

Apparatus and method for removing selected sheets from the lower bridge of a corrugated paperboard manufacturing machine. In the present invention, a slot is provided in the upper bridge of a corrugated paperboard manufacturing machine. Under the slot, an inclined sorting conveyor is positioned at a point adjacent the lower bridge of the corrugated machine. A hold-down conveyor is also mounted on the upper bridge adjacent to the sorting conveyor such that sheets of corrugated paperboard are drivingly engaged between the two conveyors. When defective sheets of paperboard appear on the lower bridge, the machine operator activates a lever which raises fingers into position to divert the defective sheets. The defective sheets are engaged by the sorting conveyor and the hold-down conveyor and transported through the slot in the upper bridge. Sheets so removed from the stream of production are stacked and stored for disposal in a rack positioned over the upper bridge of the machine.

United States Patent [191 DiFrank et al.

[ Aug. 28, 1973 [73] Assignee: Owens-Illinois, lnc.,

Toledo, Ohio [22] Filed: Feb. 22, 1972 [21] Appl. No.: 228,018

[52] US. Cl. 209/74 R, 271/64, 83/106 [51] Int. Cl. B070 3/02 [58] Fieldof Search 209/88 S, 74 R;

[56] References Cited UNITED STATES PATENTS 6/1972 Norton 271/64 7/1949Navmann 214/11 Primary Examiner-Allen N. Knowles Assistant Examiner-GeneA. Church Attomey-Steve M. McLary et al.

[57] ABSTRACT Apparatus and method for removing selected sheets from thelower bridge of a corrugated paperboard manufacturing machine. In thepresent invention, a slot is provided in the upper bridge of acorrugated paperboard manufacturing machine. Under the slot, an inclinedsorting conveyor is positioned at a point adjacent the lower bridge ofthe corrugated machine. A hold-down conveyor is also mounted on theupper bridge adjacent to the sorting conveyor such that sheets ofcorrugated paperboard are drivingly engaged between the two conveyors.When defective sheets of paperboard appear on the lower bridge, themachine operator activates a lever which raises fingers into position todivert the defective sheets. The defective sheets are engaged by thesorting conveyor and the hold-down conveyor and transported through theslot in the upper bridge. Sheets so removed from the stream ofproduction are stacked and stored for disposal in a rack positioned overthe upper bridge of the machine.

12 Claims, 5 Drawing Figures Patented Aug. 28, 1973 4 Sheets-Sheet 1Patented Aug. 28, 1973 4 Sheets-Sheet 7:

APPARATUS AND METHOD FOR REMOVING SELECTED SHEETS FROM THE LOWER BRIDGEOF A CORRUGATED PAPER BOARD MANUFACTURING MACHINE BACKGROUND OF THEINVENTION This invention generally relates to machines for themanufacture of corrugated paperboard. More particularly, this inventionrelates to apparatus and method for removing selected sheets ofpaperboard from the lower bridge of such a machine. Most specifically,this invention relates to apparatus and method for selectively divertingsheets of paperboard which exhibit defects to conveyors which propel therejected sheets through a slot formed in the upper bridge of the machineto a holding rack.

Corrugated paperboard is manufactured in a continuous web of a width ofas much as 80 or more inches. As the final step in the manufacturingprocess, this continuous web is longitudinally slit into several stripsof a lesser width. These strips are then diverted to an upper or alower-bridge assembly near the end of the corrugated manufacturingmachine. The purpose of diverting strips up or down is to allow thestrips to be transversely slit into discrete sheets of paperboardmaterial of differing lengths. Methods of sorting sheets of materialhave been known in the prior art, such as the apparatus shown in US.Pat. No. 2,476,371. However, to date, no suitable system for removingpaperboard sheets from the lower bridge of a corrugated machine has yetbeen devised. The necessity of removing sheets from the lower bridgeresults from the occurence of splices in the continuous web ofpaperboard material. These splices cause disruptions in downstreamoperation and frequently lead to the jamming of stacking equipment.Previous to this time, the defective sheets on the lower bridge had beendiverted downward under the bridge or had been physically removed fromthe bridge section by the operator. However, this process has not provensatisfactory, since the rejected sheets tend to accumulate underfoot andpresent an unsatisfactory condition. Those skilled in the art hadassumed that it was impossible to reject sheets through the upper-bridgeportion. However, we have devised an apparatus and a method which allowsdefective sheets to be rejected upward through the upper bridge and thusto a location where they may be handled most efi'lciently.

SUMMARY OF THE INVENTION This invention is an apparatus for separatingselected sheets of corrugated paperboard from a flow of paperboard onthe lower bridge of a superposed, two-bridge corrugator comprising meanson said lower bridge for deflecting the leading edge of selected sheetsupward from the plane of the lower bridge, and means positioned abovesaid lower bridge for grasping and upwardly propelling the deflectedsheets through an opening formed in the upper bridge.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. I is a schematic,side-elevational view of the longitudinal and transverse slittingportions of a corrugated paperboard manufacturing machine showing thepaper-board-diverting apparatus of the present invention in itsoperational environment;

FIG. 2 is a side-elevational view of the apparatus of the presentinvention;

FIG. 3 is a perspective view of the paper pickup por tion of theapparatus of the present invention (shown in FIG. 2);

FIG. 4 is a perspective view from above of the upperbridge area of theapparatus of the present invention illustrating the exit end of thediverting apparatus; and

FIG. 5 is a view similar to FIG. 4 illustrating the invention as appliedto an alternative design of the surface of the top bridge of thecorrugated paperboard machine.

DETAILED DESCRIPTION OF THE DRAWINGS As seen in FIG. 1, a continuous webof corrugated paperboard 10 is fed into a longitudinal slitting device12. The continuous web of paperboard 10 at this point may be eightyinches or more wide. The purpose of the slitting device 12 is to cut the-inch width into widths suitable for manufacture into corrugated boardproducts. Thus, the slitting device 12 will normally cut the width ofthe web 10 into three discrete widths. After the slitting operation, thestrips of corrugated material are fed out of the slitting device 12 andare diverted either upward or downward from the original plane of theweb 10. The diversion is done by means of diverting slats such as 14 and15 whose operation is controlled by air motors l6 and 17. For ease ofexplanation, in this case it has been assumed that the web 10 has beenslit into only two strips I8 and 20. However, it should be realized thatunder normal conditions where three strips are formed, two strips may bediverted upward and one strip downward or vice versa. The purpose indiverting the strips 18 and 20 upward or downward is to allow the nowlongitudinally slit strips to be transversely cut into individual sheetsof paperboard for final processing. The transverse cuts to produceindividual sheets are accomplished in the knife section 22. It will berecognized that the knife section 22 contains two independentlycontrolled knives. This allows the upper strip 18 to be transversely cutinto individual sheets of one length while the lower strip 20 may betransversely cut into sheets of a different length. Thus, the normalpurpose of the knife section 22 is to allow the production of sheets ofdifferent lengths from the upper strip 18 and the lower strip 20. Theknife section 22 shown in FIG. 1 is one of two possible configurationscommonly in commercial use today. The configu ration shown in FIG. 1illustrates a back-to-back knife system. That is, the knife section 22transversely cuts both the upper strip 18 and the lowerv strip 20 atessentially the same location along the flow of material. Thus, from theexit of the knife section 22 emerge individual upper sheets 24 andindividual lower sheets 26. The upper sheets 24 are fed ontoanupper-bridge assembly 28. The lower sheets 26 are fed onto alowerbridge assembly 30. Suitable support columns 32 and 33 serve tosupport and separate the upper bridge 28 and lower bridge 30. The termbridge" has been used to refer to the supporting framework which may beactually seen in FIG. 1. The bridges 28 and 30 in the embodiment shownin FIG. I serve to support a plurality of moving belt-type conveyors,best seen in FIGS. 3 and 4, which convey the upper sheets 24 and lowersheets 26 to a take-out conveyor 34. Only the lower take-out conveyor 34is shown in FIG.. I, it being understood that there is an upper take-outconveyor substantially identical to the lower take-out conveyor 34-butsome what further downstream and thus not shown.

As previously noted, it is possible to utilize a somewhat differenttransverse knife-cutting arrangement than that shown in FIG. 1. Thoseskilled in the corrugating art will readily recognize the differences inthe system and a short explanation should suffice to explain thedifferences. In the alternative system, the transverse cutting is donein what is called a split-knife systern. In the split-knife system, onlythe lower strip 20 is cut into transverse individual sheets 26immediately after the diverting slats I4 and 15. Thus, the lower bridge30 in such a case still serves to carry a plural belt conveyor system tomove the lower sheets 26 to the lower take-out conveyor 34. However, theupper strip 18 is not out immediately, but rather is pulled downstreamby a separate transverse cutting knife located beyond the lower take-outconveyor 34. In this situation, the upper bridge 28 does not carry atrue conveying system, but rather is simply a flat slide plate overwhich the upper strip 18 is pulled by the transverse cutting knivesuntil it is cut into discrete upper sheets 24.

The sheet-ejecting apparatus, generally designated 36, of the presentinvention is shown in its operational position in FIG. 1. Due to thesmall scale of FIG. 1, reference should now be made to FIG. 2 for afuller understanding of the operation of the sheet-ejecting apparatus 36of the present invention.

As seen in FIG. 2, an inclined sorting conveyor 38 has its upper endsupported by the upper bridge 28 which carries a rotatable drive shaft40. The sorting conveyor 38 is driven by an electric motor 42, alsocarried by the upper bridge 28. The lower portion of the sortingconveyor 38 is supported adjacent the lower bridge 30 by a bracket 44supported by the lower bridge 30. Mounted in the bracket 44 is arotatable idler shaft 46 for the lower portion of the sorting conveyor38. An inclined hold-down conveyor 48 is supported from the upper bridge28 through two support brackets 50, only one of which is seen in FIG. 2.The hold-down conveyor 48 is further defined by two frame members 52,only one of which is seen in FIG. 2. The frame members 52 extend fromthe support bracket 50 downward to a point adjacent the lower bridge 30at a point upstream (it being appreciated that the flow of paperboard isfrom left to right in FIG. 2) of the termination point of the sortingconveyor 38. It may readily be seen that the hold-down conveyor 48 ispositioned so that it overlies the sorting conveyor 38 for a substantialportion of the length of the two conveyors. The hold-down conveyor 48 ispivotally supported on the support brackets 50 by a drive shaft 54mounted in the support brackets 50. An electric drive motor 56 serves topower the hold-down conveyor 48. An idler shaft 58 is rotatably mountedbetween the two frame members 52 at the lower end thereof. Adjacent theidler shaft 58, an attachment member 60 is fixed to the frame member 52.The attachment member 60 shown in FIG. 2 is a conventional hook-typemember, and serves to attach a cable 62 to the frame member 52. Thecable 62 is directed upward and around a sprocket 64. Passing over thesprocket 64, the cable 62 is directed in a substantially horizontal pathto a cable connector 66 which attaches the end of the cable 62 to therod 68 of an air motor 70. The air motor 70 and the sprocket 64 are bothattached to the upper bridge 28. With the rod 68 of the air motor 70extended as shown in FIG. 2, the hold-down conveyor 48 overlies thesorting conveyor 38 in such a manner that any sheets 26 which are passedbetween the two conveyors will be grasped and engaged in such a mannerthat they will be fed up the length of the sorting conveyor 38. If therod 68 of the air motor 70 is retracted, the lower end of the holddownconveyor 48 will be raised upward, thus providing an open space in whichany necessary maintenance work may be done. This feature is also usefulin the event that a sheet 26 should jam between the holddown conveyor 48and the sorting conveyor 38. The air motor 70 is cycled by theintroduction of air under pressure through the inlet line 71 or outletline 69 under the control of a suitable valving system. One such systemcould be a hand-operated four-way valve 73 connected to a source ofhigh-pressure air 75 by a suitable pipeline 77. A portion of the upperbridge 28 is cut away in FIG. 2 to show a transverse slot or opening 72through which sheets 26 that are diverted from the lower bridge arepassed onto the upper bridge 28. This transverse slot 72 thus dividesthe upper-bridge paperboard supporting surface into two distinctsegments. These segments will best be understood by reference to FIGS. 4and 5 and will be discussed in conjunction with these drawings. A seriesof non-powered pressure rolls 74 are mounted on a shaft 76 carried by apivot arm 78 attached to the lower bridge 30. The pressure rolls 74serve the purpose of keeping the sheets 26 in contact with the conveyingsurface of the lower bridge 30. In addition, a connecting rod 80 isattached to a rock shaft 82 which carries a plurality of spaced fingers92 for diverting sheets 26 (see FIG. 3). A crank 84 is located at theend of the connecting rod 80 to allow an operator to rotate theconnecting rod 80 to raise the fingers 92 and thus divert sheets 26 intothe nip of the hold-down and sorting conveyors 48 and 38.

Turning now to FIG. 3, it may be seen that the holddown conveyor 48 isshown in phantom lines. This is done solely for the purposes of clarity,since the holddown conveyor 48 actually completely overlies the sortingconveyor 38 and would, if fully drawn, hide the features of the sortingconveyor 38 which it is desired to illustrate. The actual configurationof the hold-down conveyor 48 may best be seen by reference to FIGS. 4and 5. The sorting conveyor 38 is actually composed of a number ofendless conveyor belts 86 trained around idler sprockets 88 carried bythe idler shaft 46 and corresponding drive sprockets 90 (see FIG. 4)carried by the drive shaft 40. The idler shaft 46 and drive shaft 40 Icarry a plurality of idler sprockets 88 and drive sprockets 90 extendingsubstantially across the entire width of both bridges 28 and 30. This,of course, means that there is a corresponding plurality of conveyorbelts 86 which effectively span the width of the lower bridge 30. It maybe appreciated that the widths of the lower bridge 30 and the upperbridge 28 are substantially equal. It may also be seen in FIG. 3 that aplurality of pressure rolls 74 are carried by the pressure roll shaft76. Again, these pressure rolls 74 are spaced substantially across theentire width of the lower bridge 30. In FIG. 3, the connecting rod 80which moves the rock shaft 82 has been removed for clarity. It may beseen that the rock shaft 82 carries a plurality of lifting fingers 92 onit. The lower bridge 30 has been removed in FIG. 3 so that the conveyingsystem for the lower bridge may be seen. A drive shaft 94 carries aplurality of drive sprockets 96. The drive shaft 94 is rotatablysupported by both sides of the lower bridge 30. The drive shaft 94 isdriven in the usual manner by suitable drive means which is not shown.The plurality of drive sprockets 96 are spaced on the shaft 94 and spansubstantially the entire width of the lower bridge 30. It may beappreciated that at the opposite end of the lower bridge there is acorresponding idler shaft and idler sprockets which are not shown. Aplurality of endless conveyor belts 98 are trained around the drivesprockets 96 and the idler sprockets to form a conveying surface for thelower bridge 30. Thus, it can be seen that paperboard sheets 26 movingalong the lower bridge 30 are conveyed by the multiple conveyor belts98. When a sheet containing a splice reaches the vicinity of the fingers92, the operator of the machine moves the crank 84, in turn rotating orrocking the connecting rod 80 and the shaft 82. This motion raises thelifting fingers 92 and thus deflects the sheet 26 upward over thepressure rolls 74. The net result is that the sheet 26 is trappedbetween the hold-down conveyor 48 and the sorting conveyor 38 and ismoved upward along the incline of the conveyor 38 toward the transverseslot 72 in the upper bridge 28.

FIG. 4 clearly illustrates the emergence of a rejected lower sheet 26through the transverse slot 72 in the upper bridge 28. It may also benoted that there will a]- ways be a gap available in the stream ofsheets 24 on the upper bridge 28 which allows passage of the rejectedlower sheet 26. That is, it will be recalled that atthe point at whichthe slit strips 18 and 20 are diverted, a portion of the entire width ofthe continuous web goes up and a portion goes down. Thus, since thebridges 28 and 30 are the full width of the continuous web 10, a spacewill occur where the corresponding strip has been diverted up or down.In the case illustrated in FIG. 4, the space occurs on the outside ofthe upper bridge 28. That is, sheets 24 are conveyed only on the insideportion of the width of the upper bridge 28. Conversely, lower sheets 26are conveyed only on the outside portion width of the lower bridge 30.Thus, when a rejected sheet 26 exits through thetransverse slot 72,there is no material in its path of progress, and

it may be easily diverted into a holding bin 35 sup-- ported above theupper bridge 28. The hold-down conveyor 48 may now be seen to be acontinuous belt-type conveyor which extends the entire width of theupper bridge 28 and the lower bridge 30. This is in contrast to theconfiguration of the sorting conveyor 38 which is made up of a pluralityof conveyor belts 86. The conveyor 48 is composed of a conveyor belt 100trained around an upper-drive roll 102 and a lower-idler roll 104 (seeFIG. 2). In addition, the paperboard supporting surface of the upperbridge 28, in the embodiment shown in FIG. 4, is made up of two distinctconveyor sections. The upstream conveyor section is made up of aplurality of endless conveyor belts 106 trained over a plurality ofdrive sprockets 108 carried by a drive shaft 110. At the end of theupper conveying unit adjacent the slitting unit 22, there is acorresponding series of idler sprockets and an idler shaft which are notshown. In the apparatus of the prior art, this upper conveyIng systemwas continuous and thus substantially identical to the conveying systempreviously discussed in conjunction with the lower bridge 30. However,to

' provide the transverse gap 72, the upper bridge 28 conveying systemhas been split into the two distinct portions shown in FIG. 4. Thedownstream portion of the upper bridge 28 conveying system may be seento be likewise comprised of a plurality of endless driven belts 112trained over a corresponding plurality of idler sprockets 114 carried byan idler shaft 116. At the termination of the downstream section of thesplit conveyor for the upper bridge 28, there will be a correspondingplurality of driven sprockets and a drive shaft (not shown). The splitupper-conveyor system may be driven from a common drive means through achaindrive system which is not shown.

FIG. 5 illustrates a second configuration or design of the upper bridge28 which is used when the split-knife system discussed in conjunctionwith FIG. 1 is utilized rather than the back-to-back knife system whichis illustrated in FIG. 1. The apparatus of the present invention isidentical, whichever system is used; therefore, the same referencenumerals for the present apparatus are used in FIG. 5 as are used inFIG. 4. It will be noted that the major difference is that the upperconveying system shown in FIG. 4 has been replaced by a downstream slideplate 120 and an upstream slide plate 118. The transverse slot 72through which the rejected sheets 26 may pass is now formed by theseparation of the slide plate into a downstream slide plate 120 andupstream slide plate 118. It will also be noted that in thisconfiguration,-the paperboard traveling over the upper bridge 28 is nolonger in the form of individual upper sheets 24, but rather retains itsidentity as a continuous strip 18, being cut into individual sheets 24only after it has passed over the upper bridge 18.

It may now be appreciated that the apparatus of the present inventionwill function to reject selected lower sheets 26 regardless of the knifesystem utilized and re- 'gardless of the configuration of the paperboardon the upper bridge 28. The general operation of the apparatus of thepresent invention is as follows: the operator of the slitting equipmentwill receive a warning from the operator of the corrugating section thata splice has been made in the paperboard. Upon receipt of this warning,the operator will position himself adjacent the connecting rod and crank84. He will then observe the passing sheets 26 until such time as hesees the approach of the sheet 26 which carries the splice. that is tobe removed. It should be noted that more than one sheet 26 may showevidence of the splice in the paperboard, and the operator mayaccordingly reject two or more sheets as the circumstances require. Whenthe sheet 26 which is to be rejected approaches the vicinity of thelifting fingers 92, the operator moves the crank 84, thereby moving theconnecting rod 80 and the rock shaft 82. This motion pivots the liftingfingers 92 upward and diverts the sheet 26 over the pressure rolls 74and brings it into engagement with the hold-down conveyor 48 and thesorting conveyor 38. At this point, the hold-down conveyor 48 and thesorting conveyor 38 drivingly engage the sheet 26 and force it upwardand out the transverse slot 72 in the upper bridge 28. The rejectedsheet 26 is forced 'into the holding bin 35 by virtue of the velocityimparted to it from the hold-down conveyor 48 and the sorting conveyor38.

It should be clear that the upward velocity of the hold-down conveyor 48and the sorting conveyor 38 must be greater than the velocity of thesheets 26 along the lower bridge 30. If this were not so, a directedsheet 26 would be slowed as it started upward toward the transverse slot72. In such a'case, the diverted sheet 26 could be rammed by a followingsheet 26, thus leading to a jam in the flow.

ln addition, the upstream portion of the hold-down conveyor 48 whichdoes not overlie the sorting conveyor 38 serves an important guidingfunction. As a sheet 26 is diverted upward by the fingers 92, the sheetwill strike the underside of this upstream portion of the hold-downconveyor 48. This will help guide the sheet 26 over the pressure rolls74 until it is caught in the nip between the hold-down conveyor 48 andthe sorting conveyor 38.

What I claim is:

1. Apparatus for removing selected sheets from a lower bridge of amachine for manufacturing corrugated paperboard which longitudinallysplits a continuous web of paperboard into a plurality of strips anddiverts a portion of said strips to an upper bridge and the remainder ofsaid strips to a lower bridge, the strips being diverted to the lowerbridge having been transversely slit into discrete sheets subsequent todiversion and prior to entering onto said lower bridge, comprising, incombination: an upper-bridge paperboard supporting surface split intotwo discrete segments defining a transverse opening extending the fullwidth of said upper bridge; means located intermediate said upper andlower bridges below said transverse opening for transporting sheets ofpaperboard from said lower bridge to said upper bridge through saidtransverse opening; and selectively operable sheet-engaging meanslocated adjacent said lower bridge for diverting selected sheets ofpaperboard from said lower bridge into said means for transportingsheets of paperboard from said lower bridge to said upper bridge.

2. The apparatus of claim 1, wherein said means for transporting sheetsof paperboard from said lower bridge to said upper bridge through saidtransverse opening comprises, in combination: an inclined sortingconveyor having one end thereof supported adjacent the downstream sideof said transverse opening and having the other end thereof supportedadjacent said lower bridge; an inclined hold-down conveyor partiallyoverlying said sorting conveyor, one end of said holddown conveyor beingsupported adjacent the upstream side of said transverse opening, andhaving the other end thereof supported adjacent said lower bridgeupstream of said sorting conveyor, the relative vertical positioning ofsaid sorting and hold-down conveyors being such that a sheet ofpaperboard can be drivingly engaged by both conveyors; and means fordriving said sorting and hold-down conveyors such that adjacent surfacesare moving in the direction of said transverse opening.

3. The apparatus of claim 2, wherein said sorting conveyor comprises, incombination: a rotatable drive shaft supported by said upper bridge; aplurality of drive pulleys carried by said drive shaft; a rotatableidler shaft carried by a bracket supported by said lower bridge; aplurality of idler sprockets carried by said idler shaft; and aplurality of endless belts trained over said idler and drive pulleys insequence.

4. The apparatus of claim 2, wherein said hold-down conveyor comprises,in combination: two spaced-apart, elongated frame members pivotallymounted on two support brackets carried by said upper bridge; arotatable drive shaft carried by said frame members and said supportbrackets; a drive roll positioned between said frame members and carriedby said drive shaft; a rotatable idler shaft supported by saidspaced-apart frame members at the end of said frame members oppositesaid drive shaft; an idler roll positioned between said frame membersand carried by said idler shaft; an endless belt having a widthsubstantially equal to the distance between said frame members trainedaround said drive and idler rolls; and retractable suspension meanscarried by said upper bridge for supporting the end of said framemembers carrying said idler shaft and idler roll.

5. The apparatus of claim 4, wherein said suspension means comprises, incombination: a cable attachment member fixed to at least one of saidframe members adjacent said idler shaft; an air motor mounted on saidupper-bridge member having an extensible actuating rod carrying a cableconnector on its extending end; a rotatable pulley mounted on said upperbridge substantially on the center line of said air motor and positionedsubstantially vertically above said cable attachment member; a cabletrained over said pulley and attached to said cable attachment memberand said cable connector; and means for operating said air motor toraise said hold-down conveyor away from its paperboardengaging positionwith said sorting conveyor.

6. The apparatus of claim 1, wherein said selectively operablesheet-engaging means comprises, in combination: a rock shaft pivotallymounted on said lower bridge adjacent said hold-down and sortingconveyors; a plurality of fingers mounted on said rock shaft andnormally located in a position below the plane of sheets of paperboardpassing over said lower bridge; and an operating lever attached to saidrock shaft for pivoting said rock shaft to thereby raise said fingersinto a position to intercept and divert sheets of paperboard intoengagement with said hold-down and sorting conveyors.

7. The apparatus of claim 1, wherein said upperbridge paperboardsupporting surface comprises a pair of spaced-apart conveyors eachcomposed of a plurality of moving endless conveyor belts.

8. The apparatus of claim 1, wherein said upperbridge paperboardsupporting surface comprises a pair of spaced-apart substantiallyhorizontal slide plates.

9. The apparatus of claim 1, further including a paperboard receivingbin positioned above said upper bridge and substantially in alignmentwith the downstream edge of said transverse opening for receivingpaperboard sheets diverted from said lower bridge.

10. A method of removing selected sheets from a lower bridge of amachine for manufacturing corrugated paperboard which longitudinallysplits a continuous web of paperboard into a plurality of strips anddiverts a portion of said strips to an upper bridge and the remainder ofsaid strips to a lower bridge, the strips being diverted to the lowerbridge having been transversely split into discrete sheets subsequent todiversion and prior to entering onto said bridge, comprising the stepsof:

diverting selected sheets upward from the plane of sheet travel alongsaid lower bridge; and

propelling said diverted sheet upward through a transverse openingformed in said upper bridge.

11. A method according to claim 10, wherein the step of propelling saiddiverted sheet upward through a transverse opening formed in said upperbridge comprises the steps of:

confining said selected sheets between two upwardly moving beltconveyors; and

transporting said selected sheets at a speed sufficient to pass saidsheets through said transverse opening.

12. The method of claim 10, further including the step of stacking saidselected sheets in a bin positioned over said upper bridge.

1. Apparatus for removing selected sheets from a lower bridge of amachine for manufacturing corrugated paperboard which longitudinallysplits a continuous web of paperboard into a plurality of strips anddiverts a portion of said strips to an upper bridge and the remainder ofsaid strips to a lower bridge, the strips being diverted to the lowerbridge having been transversely slit into discrete sheets subsequent todiversion and prior to entering onto said lower bridge, comprising, incombination: an upper-bridge paperboard supporting surface split intotwo discrete segments defining a transverse opening extending the fullwidth of said upper bridge; means located intermediate said upper andlower bridges below said transverse opening for transporting sheets ofpaperboard from said lower bridge to said upper bridge through saidtransverse opening; and selectively operable sheet-engaging meanslocated adjacent said lower bridge for divertIng selected sheets ofpaperboard from said lower bridge into said means for transportingsheets of paperboard from said lower bridge to said upper bridge.
 2. Theapparatus of claim 1, wherein said means for transporting sheets ofpaperboard from said lower bridge to said upper bridge through saidtransverse opening comprises, in combination: an inclined sortingconveyor having one end thereof supported adjacent the downstream sideof said transverse opening and having the other end thereof supportedadjacent said lower bridge; an inclined hold-down conveyor partiallyoverlying said sorting conveyor, one end of said hold-down conveyorbeing supported adjacent the upstream side of said transverse opening,and having the other end thereof supported adjacent said lower bridgeupstream of said sorting conveyor, the relative vertical positioning ofsaid sorting and hold-down conveyors being such that a sheet ofpaperboard can be drivingly engaged by both conveyors; and means fordriving said sorting and hold-down conveyors such that adjacent surfacesare moving in the direction of said transverse opening.
 3. The apparatusof claim 2, wherein said sorting conveyor comprises, in combination: arotatable drive shaft supported by said upper bridge; a plurality ofdrive pulleys carried by said drive shaft; a rotatable idler shaftcarried by a bracket supported by said lower bridge; a plurality ofidler sprockets carried by said idler shaft; and a plurality of endlessbelts trained over said idler and drive pulleys in sequence.
 4. Theapparatus of claim 2, wherein said hold-down conveyor comprises, incombination: two spaced-apart, elongated frame members pivotally mountedon two support brackets carried by said upper bridge; a rotatable driveshaft carried by said frame members and said support brackets; a driveroll positioned between said frame members and carried by said driveshaft; a rotatable idler shaft supported by said spaced-apart framemembers at the end of said frame members opposite said drive shaft; anidler roll positioned between said frame members and carried by saididler shaft; an endless belt having a width substantially equal to thedistance between said frame members trained around said drive and idlerrolls; and retractable suspension means carried by said upper bridge forsupporting the end of said frame members carrying said idler shaft andidler roll.
 5. The apparatus of claim 4, wherein said suspension meanscomprises, in combination: a cable attachment member fixed to at leastone of said frame members adjacent said idler shaft; an air motormounted on said upper-bridge member having an extensible actuating rodcarrying a cable connector on its extending end; a rotatable pulleymounted on said upper bridge substantially on the center line of saidair motor and positioned substantially vertically above said cableattachment member; a cable trained over said pulley and attached to saidcable attachment member and said cable connector; and means foroperating said air motor to raise said hold-down conveyor away from itspaperboard-engaging position with said sorting conveyor.
 6. Theapparatus of claim 1, wherein said selectively operable sheet-engagingmeans comprises, in combination: a rock shaft pivotally mounted on saidlower bridge adjacent said hold-down and sorting conveyors; a pluralityof fingers mounted on said rock shaft and normally located in a positionbelow the plane of sheets of paperboard passing over said lower bridge;and an operating lever attached to said rock shaft for pivoting saidrock shaft to thereby raise said fingers into a position to interceptand divert sheets of paperboard into engagement with said hold-down andsorting conveyors.
 7. The apparatus of claim 1, wherein saidupper-bridge paperboard supporting surface comprises a pair ofspaced-apart conveyors each composed of a plurality of moving endlessconveyor belts.
 8. The apparatus of claim 1, wherein said upper-bridgepaperboard supporting surface comprisEs a pair of spaced-apartsubstantially horizontal slide plates.
 9. The apparatus of claim 1,further including a paperboard receiving bin positioned above said upperbridge and substantially in alignment with the downstream edge of saidtransverse opening for receiving paperboard sheets diverted from saidlower bridge.
 10. A method of removing selected sheets from a lowerbridge of a machine for manufacturing corrugated paperboard whichlongitudinally splits a continuous web of paperboard into a plurality ofstrips and diverts a portion of said strips to an upper bridge and theremainder of said strips to a lower bridge, the strips being diverted tothe lower bridge having been transversely split into discrete sheetssubsequent to diversion and prior to entering onto said bridge,comprising the steps of: diverting selected sheets upward from the planeof sheet travel along said lower bridge; and propelling said divertedsheet upward through a transverse opening formed in said upper bridge.11. A method according to claim 10, wherein the step of propelling saiddiverted sheet upward through a transverse opening formed in said upperbridge comprises the steps of: confining said selected sheets betweentwo upwardly moving belt conveyors; and transporting said selectedsheets at a speed sufficient to pass said sheets through said transverseopening.
 12. The method of claim 10, further including the step ofstacking said selected sheets in a bin positioned over said upperbridge.